1. Field of the Invention
This invention relates to a catalyst for polymerization of olefin monomers, and more particularly to a catalyst which can give, with high yields, polymers having high stereoregularity when used for polymerization of olefin monomers having three or more carbon atoms.
To polymerize olefin monomers having three or more carbon atoms such as propylene monomers by using a conventional catalyst, the monomers are, in general, subjected to what is called preliminary polymerization before conducting main polymerization; otherwise a polymer having high stereoregularity would not be obtained in a powder state having good properties such as bulk density, particle size distribution. The catalyst according to the present invention, however, does not require such a process of preliminary polymerization of
2. Description of the Related Art
In recent years, there have been proposed various methods for preparing polymers having high stereospecificity, in which .alpha.-olefin monomers having three or more carbon atoms are subjected to stereospecific polymerization in the presence of a solid catalyst component containing as requisite components titanium, magnesium and a halogen. In the above conventional methods, a process of preliminary polymerization of the monomers may be indispensable. In most cases, however, preliminary polymerization of the catalyst employed. For this reason, there has been a demand for the development of a catalyst suitable for polymerization of olefin monomers having three or more carbon atoms, which does not require a process of preliminary polymerization of monomers, and can give polymers having high stereospecificity.